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ABOUT THIS IMAGE:

The giant elliptical galaxy in the center of this image, taken by NASA's Hubble
Space Telescope, is the most massive and brightest member of the galaxy cluster
Abell 2261.

Spanning a little more than one million light-years, the galaxy is about 10 times the diameter of our
Milky Way galaxy. The bloated galaxy is a member of an unusual class of galaxies
with a diffuse core filled with a fog of starlight. Normally, astronomers would
expect to see a concentrated peak of light around a central black hole. The Hubble
observations revealed that the galaxy's puffy core, measuring about 10,000
light-years, is the largest yet seen.

The observations present a mystery, and studies of this galaxy may provide insight
into how black hole behavior may shape the cores of galaxies.

Astronomers used Hubble's Advanced Camera for Surveys and Wide Field Camera 3 to
measure the amount of starlight across the galaxy, dubbed A2261-BCG. Abell 2261
is located three billion light-years away.

The observations were taken March to May 2011. The Abell 2261 cluster is part of
a multi-wavelength survey called the Cluster Lensing And Supernova survey with
Hubble (CLASH).